Measurement system and method for generating a trigger signal for a measurement system

ABSTRACT

A measurement system has an analog channel comprising an analog-to-digital converter for converting an external analog input signal into a corresponding digital input signal, an external trigger input for receiving an external trigger signal comprising a comparator configured to compare the external trigger signal against a trigger threshold signal for generating a binary trigger signal, and a digital signal processing unit. The digital signal processing unit comprises a digital trigger unit configured to receive the digital input signal and to generate at least one trigger event signal based on the digital input signal, and a trigger logic unit configured to receive the at least one trigger event signal and the binary trigger signal to generate a combined trigger signal. Further, a method for generating a trigger signal for a measurement system is described.

FIELD OF DISCLOSURE

Embodiments of the present disclosure relate to a measurement system anda method for generating a trigger signal for a measurement system. Inparticular, embodiments of the present disclosure relate to anoscilloscope and a method for generating a trigger signal for anoscilloscope.

BACKGROUND

A measurement system, such as an oscilloscope, is an electronics testand measurement instrument used to acquire, analyze and display awaveform of one or several signals under test (also referred to as“measurement signals”). The measurement signals may be generated by adevice under test and may be analog or digital signals. Modernmeasurement systems continuously acquire and store samples of themeasurement signals.

Typically, a measurement system comprises a trigger system that capturessignal events for detailed analysis and provides a stable view ofrepeating waveforms of the measurement signals by always starting thedrawing of the waveform on a display of the measurement system inresponse to detection of a so-called trigger event.

The detection of a trigger event provides a reference point of time. Inother words, the trigger system enables a user of the measurement systemto acquire, display and analyze signals relative to a specific point intime defined by the trigger event. For example, a measurement system maybe used to analyze and debug a complex digital circuit such as amicroprocessor to identify events that cause faults or malfunction ofthese digital circuits. Modern measurement systems are able to detecttrigger events from a plurality of signals, even an external triggersignal.

In other words, the trigger event may be a compound trigger event andmay be detected from a combination of a plurality of signals.

A measurement system may comprise a digital trigger system that operatesdirectly on the samples of the measurement signals acquired by themeasurement system. In other words, the digital trigger system processesthe identical signals or signal samples that are acquired and displayedby the measurement system. A digital trigger system provides reducedtrigger jittering, the possibility of real-time triggering based onsignals that have been digitally pre-processed (e.g. real-timede-embedding, an HD mode) and a trigger hysteresis that is preciselyadjustable.

There is a need for a measurement system having a versatile digitaltrigger system that is able to generate trigger signals based on signalsto be measured and/or an external trigger signal.

SUMMARY

Embodiments of the present disclosure provide a measurement systemhaving at least one analog channel comprising an analog-to-digitalconverter configured to convert an external analog input signal into acorresponding digital input signal; an external trigger input forreceiving an external trigger signal and comprising a comparatorconfigured to compare the external trigger signal against a triggerthreshold signal for generating a binary trigger signal; and a digitalsignal processing unit. The digital signal processing unit in someembodiments comprises a digital trigger unit configured to receive thedigital input signal and to generate at least one trigger event signalbased on the digital input signal, and a trigger logic unit configuredto receive the at least one trigger event signal and the binary triggersignal to generate a combined trigger signal.

In other words, a measurement system is provided with a digital triggersystem, wherein, in order to generate a trigger signal, the digitalsignal processing unit of the measurement system is configured togenerate a trigger signal based on digital input signals converted fromexternal analog input signals as well as a binary trigger signalgenerated from an external trigger signal by comparing the externaltrigger signal against a trigger threshold signal.

Hence, the external trigger signal, as well as one or more of theexternal analog input signals, may be used as a source for generating atrigger signal for the measurement system. Accordingly, the generatedtrigger signal is a combined trigger signal. Thus, the advantages of thedigital trigger system of the measurement system are combined with theuse of an external trigger.

To that end, the digital signal processing unit processes the digitalinput signals converted by and received from the at least one analogchannel and the binary trigger signal generated by and received from theexternal trigger input and generates the combined trigger signal basedon the digital input signals and the binary trigger signal.

The measurement system may be an oscilloscope, for example a digitalsampling oscilloscope. The external analog input signals may bemeasurement signals, that is, signals to be measured and analyzed by themeasurement system.

The external analog input signals may be a voltage signal and/or acurrent signal. Accordingly, the external trigger signal may be avoltage signal and/or a current signal. The external trigger signal maybe a digital signal or an analog signal.

The trigger threshold signal may also be referred to as the triggerlevel.

In some embodiments, the binary trigger signal generated by thecomparator of the external trigger input from the external triggersignal may be continuous in time and may have discrete values. As such,the external trigger signal may be processed digitally.

For instance, the binary trigger signal may comprise or may berepresented by two values which may be logical values. For example, thetwo logical values may be “1” and “0”, respectively. Accordingly, thebinary trigger signal may be processed and stored as a digital signal.

In an embodiment of the disclosure, the digital trigger unit comprises acomparator. The comparator may be configured to receive one or severalthreshold values. The comparator may further be configured to compareeach one of the digital input signals against each one of the thresholdvalues, thereby generating at least one trigger event signal. Thus, alsothe incoming signals at the analog channels may be used for triggering.

For example, the trigger event signal is similar to the binary triggersignal, e.g., the trigger event signal may as well be a binary signal.That is, each one of the trigger event signals may be continuous in timeand may have discrete values. For example, each one of the trigger eventsignals may be processed and stored as a digital signal.

In an aspect, the trigger threshold signal and/or the at least onethreshold value may a single voltage value. That is, the triggerthreshold signal and/or the threshold values may each represent apredetermined voltage value against which the external trigger signaland the digital input signals are compared against, respectively. Hence,external voltage signals may be measured and analyzed by the measurementsystem and may be used as a source for a trigger signal by themeasurement system. Thus, the trigger signal may implement anedge-trigger.

Also, the trigger threshold signal and/or the threshold values may eachrepresent a predetermined pulse width against which the external triggersignal and the digital input signals are compared against, respectively.Accordingly, the trigger signal may implement a pulse width trigger or aglitch trigger.

The digital trigger unit may further comprise a switch matrix. Theswitch matrix may have at least one input for receiving the at least onedigital input signal, the at least one trigger event signal and/or thebinary trigger signal and may pre-process each one of the signalsallowing to use the various signals for different purposes, e.g., selecta signal to be triggered and a signal for triggering.

The switch matrix may have at least one output for outputting therespective pre-processed signals. The number of outputs may be differentfrom the number of inputs. The switch matrix may be connected to thetrigger logic unit and/or the digital trigger unit. Hence, the switchmatrix may be used to selectively pre-process the respective signalsinput via inputs and selectively forward the respective signals based onthe trigger functionality selected by the user of the measurement systemas will be later described in further detail. The pre-processingperformed by the switch matrix may be dependent on the respective signalinput via its inputs.

Furthermore, the switch-matrix may be flexibly provided at any stage ofthe processing performed by the digital signal processing unit.

According to an embodiment of the present disclosure, the measurementsystem comprises at least two of the at least one analog channel, eachone of the at least two analog channels receiving a respective externalanalog input signal and converting the respective external analog inputsignal into a corresponding digital input signal. Thus, at least twodigital input signals may be received by the digital signal processingunit. Further, the switch matrix comprised in the digital signalprocessing unit is configured to select at least one signal from the atleast two digital input signals to be processed by the digital triggerunit. Hence, the digital signal processing unit may trigger on an eventon a first external analog input signal to trigger a second externalanalog input signal.

In other words, the digital signal processing unit may trigger on anevent on a first analog channel in order to trigger a signal on a secondanalog channel. Thus, the triggering may be used to acquire and displaya trace of the second external analog input signal.

In another aspect of the disclosure, the measurement system furthercomprises an acquisition memory, wherein each one of the at least oneanalog-to-digital converter comprised in the analog channels may beconnected to the acquisition memory, wherein the acquisition memory isconfigured and used to store the respective digital input signals basedon the respective external analog input signals. This way, fully digitaltriggering of the input signal is possible.

The digital input signal may be stored in the acquisition memory assamples. For example, each sample may be a digital value. Each samplemay represent a value associated to a respective point in time of therespective digital input signal. Hence, each one of the at least onedigital input signal may be stored for further processing and analysis.For example, the samples of the digital input signals may be stored tobe displayed later once a trigger event occurs.

In yet another embodiment, the acquisition memory is connected to thetrigger logic unit for receiving the combined trigger signal and thedigital signal processing unit is configured to control the acquisitionmemory based on the combined trigger signal to selectively store the atleast one digital input signal, to selectively store samples of the atleast one digital input signals in the acquisition memory, to select aportion of the at least one digital input signal stored in theacquisition memory and/or to select a portion of samples of the at leastone digital input signal stored in the acquisition memory.

Hence, the digital signal processing unit may be configured to acquire atrace of an external analog input signal converted to a digital inputsignal by, e.g., storing samples of the digital input signal in theacquisition memory or by selecting a portion of samples of the digitalinput signal stored in the acquisition memory. In other words, thedigital processing unit associates a portion of samples of a digitalinput signal stored or to be stored in the acquisition memory to thecombined trigger signal or to a trigger event comprised in the combinedtrigger signal. The samples comprised in the associated portion may besamples that are acquired consecutively in time from the respectiveexternal analog input signal converted into the respective digital inputsignal. Based on the acquired trace, the respective external analoginput signal may be analyzed by a user.

For example, the digital signal processing unit may be configured tocontrol the acquisition memory based on a trigger event occurring on thecombined trigger signal.

In another aspect, the measurement system further comprises a displayunit and the digital signal processing unit is configured to providefrom the acquisition memory to the display unit for displaying the atleast one digital input signal, samples of the at least one digitalinput signal, a selected portion of the at least one digital inputsignal, and/or a selected portion of samples of the at least one digitalinput signal. Hence, it is possible to display the trace of the digitalinput signal represented by the samples of the digital input signal, theselected portion of the digital input signal and/or the selected portionof samples of the digital input signal. The trace may be displayed as adiagram showing the values represented by the digital input signal orthe samples of the digital input signal as a function over time. Thus,the trace of the signal may be visualized for a user.

In some embodiments, the trigger logic unit may be configured togenerate the combined trigger signal depending on a set of triggerconditions, wherein the set of trigger conditions may be based on the atleast one digital input signal, the at least one trigger event signaland the binary trigger signal. In other words, the trigger conditionsmay take into account the at least one digital input signal, the atleast one trigger event signal and the binary trigger signal.Accordingly, it is possible to adapt or select the set of triggerconditions based on the measurement signals that is the external analoginput signals to be measured and analyzed by the measurement system. Theset of trigger conditions may be selected by a user of the measurementsystem.

According to an embodiment, the set of trigger conditions is configuredto provide sequence trigger functionality, a qualified triggerfunctionality, a pattern trigger functionality, and/or an or-triggerfunctionality. Thus, depending on the set of trigger conditions used bythe digital signal processing unit, the measurement system may implementat least one of the aforementioned trigger functionalities. The set oftrigger conditions used by digital signal processing unit may beprogrammed by a user or may be selected by a user, e.g. on a userinterface of the measurement device, such as a touch screen.

The sequence trigger may comprise an ABR trigger functionality or anABCD trigger functionality.

For example, the trigger logic unit is configured to selectivelycombine, based on the set of trigger conditions, the digital inputsignal, the at least one trigger event signal and/or the binary triggersignal as trigger sources for generating the combined trigger signal. Inother words, the set of trigger conditions determines which one of thedigital input signal, the at least one trigger event signal and/or thebinary trigger signal is used by the trigger logic unit and/or how thetrigger logic unit combines the signals in order to generate thecombined trigger signal. Accordingly, the set of trigger conditionsdefines how the combined trigger signal is generated by the triggerlogic unit. Hence, the set of trigger conditions may be selected basedon, for example, the measurement signals or the behavior of the deviceunder test generating the measurement signals a user wishes to analyze.

In addition to the analog channels receiving and converting respectiveexternal analog input signals, the measurement system may comprise atleast one external digital input for receiving an external digital inputsignal. Accordingly, the digital trigger unit may be further configuredto generate the at least one trigger event signal based on the digitalinput signal and further on the external digital input signal. Forexample, when generating the combined trigger signal, the trigger logicunit may also combine the at least one digital input signal. Hence, theexternal digital input signal may also be used as trigger source. Thisallows for an improved flexibility for the user when choosing at leastone signal as trigger source for generating the combined trigger signal,since the user may choose the trigger sources among the external digitalinput signals, the external analog input signals and the externaltrigger input.

In a further aspect, the digital signal processing unit comprises a FPGAand/or an ASIC. The FPGA and/or the ASIC may comprise the digitaltrigger unit and/or the trigger logic unit. In other words, theafore-described functionality of each one of the digital trigger unitand the trigger logic unit may be implemented in hardware and/or insoftware. When the functionality of the digital trigger unit or thetrigger logic unit is implemented in software, it may be executed by thedigital signal processing unit or one or more computing devices, such asprocessors, FPGAs, ASICs, DSPs, etc.

In a further embodiment, the measurement system further comprises a userinterface unit for receiving a user input, and the set of triggerconditions, the trigger threshold signal, the at least one thresholdvalue and/or a trigger source may be based on the user input. Hence, theuser may choose the trigger according to his needs.

The trigger source for generating the combined trigger signal may befreely selected from each of the at least one analog input channelreceiving a respective external analog input signal, the digital inputchannel receiving an external digital input signal, and/or the externaltrigger input receiving an external trigger signal.

Furthermore, a method for generating a trigger signal for a measurementsystem, for example an oscilloscope, is provided. The method comprisesthe steps of:

receiving at least one external analog input signal and converting theexternal analog input signal into at least one corresponding digitalinput signal;

receiving an external trigger signal and comparing the external triggersignal against a trigger threshold signal for generating a binarytrigger signal;

generating, based on the at least one digital input signal a triggerevent signal; and

combining the trigger event signal and the binary trigger signal into acombined trigger signal.

Of course, all of the features and advantages discussed in context ofthe measurement system also apply to the method and vice versa.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of theclaimed subject matter will become more readily appreciated as the samebecome better understood by reference to the following detaileddescription, when taken in conjunction with the accompanying drawings,wherein:

FIG. 1 schematically illustrates a measurement system according to oneor more embodiments of the present disclosure;

FIG. 2A schematically illustrates a measurement system according to afirst embodiment of the present disclosure;

FIG. 2B schematically illustrates a measurement system according to asecond embodiment of the present disclosure;

FIG. 2C schematically illustrates a measurement system according to athird embodiment of the present disclosure; and

FIG. 3 is a flow diagram illustrating a method for generating a triggersignal for a measurement system according to an embodiment of thepresent disclosure.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings, where like numerals reference like elements, is intended as adescription of various embodiments of the disclosed subject matter andis not intended to represent the only embodiments. Each embodimentdescribed in this disclosure is provided merely as an example orillustration and should not be construed as preferred or advantageousover other embodiments. The illustrative examples provided herein arenot intended to be exhaustive or to limit the claimed subject matter tothe precise forms disclosed.

FIG. 1 is a high-level block diagram schematically illustrating ameasurement system 10 according to embodiments of the presentdisclosure. The measurement system 10 may be an oscilloscope, forexample a digital sampling oscilloscope. The measurement system 10 maycomprise a digital trigger system.

The measurement system 10 comprises at least one input channel 12. Insome embodiments, the measurement system 10 comprises a plurality ofinput channels 12, usually 2, 4, 8 or 16, as illustrated in FIG. 1. Eachof the input channels 12 is configured to receive a respective externalinput signal. Thus, the measurement system 10 may be configured toreceive a plurality of external input signals. Each of the externalinput signals may be an analog input signal or a digital input signal.For example, an external input signal may be a voltage or current signaland may be provided from a device under test.

Each input channel 12 may be configured to pre-process the respectiveexternal input signal. For instance, each input channel 12 may beconfigured to buffer, amplify, and attenuate the respective externalinput signal. Furthermore, in case of an analog external input signal,the respective input channel 12 comprises an analog-to-digital converterconfigured to convert the external analog input signal into a digitalinput signal.

The measurement system 10 may also comprise an external trigger input 14configured to receive an external trigger signal. The external triggerinput 14 is configured to compare the external trigger signal against atrigger threshold signal in order to generate a binary trigger signal,as will be described later in further detail.

The measurement system 10 further comprises a digital signal processingunit 16. The digital signal processing unit 16 is connected to each oneof the input channels 12 and the external trigger input 14. That, is thedigital signal processing unit 16 is configured to receive each one ofthe digital input signals and the binary trigger signal.

The digital signal processing unit 16 is further configured to generatea combined trigger signal. The combined trigger signal may be a binarysignal as well, only taking two values, for example two logical values,such as “1” and “0”.

The measurement system 10 may further comprise an acquisition memory 18connected directly to each one of the input channels 12 and to thedigital signal processing unit 16. The acquisition memory 18 may becontrolled by the digital signal processing unit 16 and it may beimplemented as RAM, for instance. In some embodiments, The acquisitionmemory 18 is controlled by the digital processing unit 16 to selectivelystore at least one digital input signal or samples of at least onedigital input signal, e.g., to store the acquired trace of an externalinput signal. The portions or samples of the digital input signal to bestored are selected based on the trigger event.

The acquisition memory 18 may also be controlled to continuously storesamples of each one of the at least one digital input signals and/or ofeach one of the external digital input signals. In this case, thedigital signal processing unit 16 is configured to acquire a trace of anexternal input signal by selecting a plurality or a portion of thesamples of the respective digital input signal or external digital inputsignal stored in the acquisition memory 18 based on the trigger event.

The measurement system 10 is configured to acquire and display a traceof one or more of the external input signals based on the combinedtrigger signal. That is, the measurement system 10 is configured toacquire and display a trace of any one of the external input signalswhen it detects a trigger event comprised in the trigger signal.

For instance, a trigger event may occur at a point in time when thecombined trigger signal changes its value or when the combined triggersignal reaches a predefined value. In case of a binary combined triggersignal, a trigger event may occur each time the combined trigger signalchanges its value, or when it reaches the value “0” or when it reachesthe value “1” or any other value.

A trace of an external input signal may be a plurality or portion ofsamples of the respective digital input signal. In case of an externalanalog input signal, the respective digital input signal is theaforementioned digital input signal converted from the external analoginput signal. In case of an external digital input signal, therespective digital input signal is the external digital input signalitself.

The measurement system 10 may further comprise a display unit 20 fordisplaying the acquired trace. The display unit 20 may be connected tothe acquisition memory 18 for receiving the acquired trace and may beconnected to the digital signal processing unit 16 for receiving acommand for displaying the acquired trace. In some embodiments, thedisplay unit 20 may be configured to display status information such asinformation about the external input signals, the combined triggersignal, or the like received from the digital signal processing unit 16.

The measurement system 10 may further comprise a user interface unit 22.In some embodiments, the user interface unit 22 may comprise a touchscreen integrated into the display unit 20. Alternatively oradditionally, the user interface unit 22 may comprise physical buttons,switches, knobs, a computer mouse, a keyboard or the like.

The user interface unit 22 is connected to the digital signal processingunit 16 and is configured to receive user input for controlling themeasurement system 10, for example the digital signal processing unit16. For example, the user may choose how the digital signal processingunit 16 generates the combined trigger signal.

For example, the user may determine at least one trigger source signal,also simply called trigger source. The trigger source signal may beselected from each one of the aforementioned at least one externalanalog input signal, the at least one external digital input signal orthe external trigger signal.

Further, the user may determine, via the user interface unit 22, whichtrigger functionality is implemented by the measurement system 10. Inother words, the user may determine the way the digital signalprocessing unit 16 generates, based on the selected trigger sources asdescribed above, the combined trigger signal.

The trigger functionality is determined based on a set of triggerconditions that take into account the selected trigger sources. Forinstance, the set of trigger conditions may be configured to provide asequence trigger functionality, a qualified trigger functionality, apattern trigger functionality, and/or an or-trigger functionality.

In some embodiments, the measurement system 10 implements anedge-trigger, a pulse width trigger and/or a glitch trigger. Forexample, the sequence trigger functionality may comprise an ABR triggerand an ABCD trigger. Furthermore, an edge-then-edge triggerfunctionality may be implemented.

Based on the set of trigger conditions, arbitrarily complex triggerconditions, that is arbitrarily complex trigger functionalities, may beimplemented by combining the aforementioned and other sets of triggerconditions known in the field.

For each functionality, a set of trigger conditions may be stored in thedigital signal processing unit 16. Thus, via the user interface unit 22,the user is able to choose which set of trigger conditions is to be usedby the digital signal processing unit 16 for generating the combinedtrigger signal.

Also, the user may determine, via the user interface unit 22, whichexternal input signals from among the at least one external input signalis used by the digital signal processing unit 16 for acquiring a tracethereof, as described above. For instance, the user may choose eitherone of the at least one external analog input signals or the externaltrigger signal as trigger source.

The measurement system 10 according to embodiments of the presentdisclosure as described in reference to FIG. 1 will now be described infurther detail with reference to FIGS. 2A to 2C.

FIG. 2A schematically illustrates a measurement system 10 according to afirst embodiment of the present disclosure. The measurement system 10comprises a number n of input channels 12 as described with reference toFIG. 1. For instance, n may be 1, 2, 4, 8 or 16.

Each one of the n input channels 12 may comprise an input 26. The input26 may be an external terminal of the measurement system 10. Forexample, the input 26 may be an electrical terminal for connecting acoaxial cable or the like for receiving an external input signal 24 suchas an external analog input signal or an external digital input signal.The n input channels 12 may simply be called analog channel or digitalchannel, depending on the external input channel received via theirrespective input 26. Each input channel 12 may comprise ananalog-to-digital-converter 30 for converting an external analog inputsignal into a digital input signal for further processing by the digitalsignal processing unit 16.

As shown in FIG. 2A, each one of the n input channels 12 is connected tothe digital signal processing unit 16 and is connected to theacquisition memory 18 via the digital signal processing unit 16. Eachone of the n input channels 12 may also be directly connected to theacquisition memory 18.

In the shown embodiment, the external trigger input 14 comprises aninput 32 similar to the input 26 of the input channels 12 that isimplemented as an electrical terminal of the measurement system 10. Viathe input 32 the external trigger input 14 may receive an externaltrigger signal 28 as described with reference to FIG. 1.

The external trigger input 14 further comprises a comparator 34 forcomparing the external trigger signal 28 against a trigger thresholdsignal. The trigger threshold signal may be a signal generatedinternally by the measurement system 10 or may also be an externalsignal received by the measurement system 10 via a further input (notshown).

The trigger threshold signal may be a signal variable over time or maybe a predetermined value. In any case, the trigger threshold signal maybe selected by a user of the measurement system 10 via the userinterface unit 22 as described with reference to FIG. 1.

The comparator 34 is configured to compare the external trigger signal28 against the trigger threshold signal for generating and outputtingthe binary trigger signal. In other words, the comparator 34 maygenerate the trigger event signal, its value being based on the outcomeof the comparison of the external trigger signal 28 with the triggerthreshold signal.

For example, the binary trigger signal may be continuous in time andtake the values “0” and “1”, which may be logical values. In case thecomparator 34 determines that the current value of the external triggersignal 28 is larger than the value of the trigger threshold signal, thecomparator 34 may determine the binary trigger signal to be “1”. In casethe comparator 34 determines that the current value of the externaltrigger signal 28 is smaller than the value of the trigger thresholdsignal, the comparator 34 may determine the binary trigger signal to be“0”.

The output of the comparator 34 is connected to the digital signalprocessing unit 16 for providing the binary trigger signal to thedigital signal processing unit 16 for further processing.

In some embodiments, the signal processing unit 16 comprises a digitaltrigger unit 36 and a trigger logic unit 38. The digital trigger unit 36is located between the input channels 12 and the trigger logic unit 38and comprises, for example, a switch matrix 40 and a comparator 42. Thetrigger logic unit 38 receives the trigger event signal from the digitaltrigger unit 36, more precisely the comparator 42, and the binarytrigger signal from the external trigger input 14, more precisely thecomparator 34.

The trigger logic unit 38 is also connected to the acquisition memory 18for controlling the acquisition of a trace of at least one of theexternal input signals 24 based on the generated combined triggersignal, as described with reference to FIG. 1.

The digital trigger unit 36, the trigger logic unit 38 and optionallythe external trigger input 14 together implement the triggerfunctionality of the digital signal processing unit 16 as described withreference to FIG. 1, e.g., based on the external digital input signalsand/or the digital input signals received from the input channels 12,the binary trigger signal received from the external trigger input 14and a set of trigger conditions.

As described with reference to FIG. 1, based on the set of triggerconditions selected by a user of the measurement system 10, the digitaltrigger unit 36 and the trigger logic unit 38 are configured to generatethe combined trigger signal implementing the respective triggerfunctionality.

Thus, by connecting both the external trigger input 14 supplying thebinary trigger signal and the input channel supplying the externaldigital input signals or the digital input signals to the digital signalprocessing unit 16, the set of trigger conditions may be formulated as acomprehensive set of trigger conditions, that is a set of triggerconditions being based on both the external input signals 24 as well asthe external trigger signal 28.

In operation, the set of trigger conditions may then be implemented bythe trigger logic unit 38, the digital trigger unit 36, or incombination by both the trigger logic unit 38 and the digital triggerunit 36.

In some embodiments, the switch matrix 40 of the digital trigger unit 36is a device configured to selectively route signals between multipleinputs and multiple outputs. The switch matrix 40 has the same number nof inputs as the number of input channels 12 but may have m outputs. Thenumber m may be the same number as the number n or it may be a differentnumber. The m outputs are connected to respective inputs of thecomparator 42.

In some embodiments, the switch matrix 40 may be configured topre-process the external digital input signals or the digital inputsignals received from the respective input channels 12. The switchmatrix 40 may also forward the external digital input signals and/or thedigital input signals to its outputs as the trigger event signal so asto select the respective signals as trigger sources. The forwarding mayhappen in accordance to the user input received via the user interfaceunit 22 as described with reference to FIG. 1.

In some embodiments, the comparator 42 is configured to compare each oneof the trigger event signals against a respective threshold signalcomprised in a plurality of threshold values. The threshold values mayeach be variable over time or may each be a predetermined value. In anycase, the threshold values may be selected by a user of the measurementsystem 10 via a user interface unit 22 as described with reference toFIG. 1.

Thus, the comparator 42 is configured to compare each one of the signalsreceived from the switch matrix against the respective trigger thresholdvalues for generating and outputting a single, a plurality or m triggerevent signals. In other words, the comparator 42 may generate triggerevent signals, the values of which being based on the outcome of thecomparison of the digital input signals with the respective thresholdvalues.

The type of trigger event signals may be the same as the type of thebinary trigger signal generated by the comparator 34 of the externaltrigger input 14 as described above.

In any case, the threshold values may be values generated internally bythe measurement system 10 or may also be external values received by themeasurement system 10 via a further input (not shown).

The outputs of the comparator 42 may be connected to the trigger logicunit 38 for supplying the trigger event signals to the trigger logicunit 38 for further processing based on the set of trigger conditionsand to ultimate generate the combined trigger signal.

FIG. 2B schematically illustrates a measurement system 10 according to asecond embodiment. The measurement system 10 corresponds to themeasurement system 10 described with reference to FIG. 2A except for thefollowing differences. A description of similar elements will beomitted, and same or functionally same parts are provided with the samereference number.

In contrast to the measurement system 10 of FIG. 2A, the measurementsystem 10 shown in FIG. 2B has the position of the switch matrix 40 andthe position of the comparator 42 comprised in the digital trigger unit36 interchanged.

In the measurement system 10 of the second embodiment, the inputchannels 12 are directly connected to the comparator 42. The comparator42 has the same number n of inputs as the number of input channels 12.Further, the comparator 42 has the number n of outputs connected to theswitch matrix 40 for supplying the trigger event signals to the triggerlogic unit 38. Alternatively, the comparator 42 may have a differentnumber of outputs and may have a functionality similar to a switchmatrix.

The switch matrix 40 has the same number of inputs for receiving thetrigger event signals as the number of outputs of the comparator 42 andmay be configured to pre-process the trigger event signals. The switchmatrix 40 has a number m of outputs connected to the trigger logic unit38 for supplying the trigger event signals selected as trigger sourcesto the trigger logic unit 38 for further processing based on the set oftrigger conditions. The number m may be the same number as the number nor it may be a different number.

The signals received by the switch matrix 40 may be selected as triggersources similarly to what has been described in reference to the switchmatrix 40 of the first embodiment.

FIG. 2C schematically illustrates a measurement system 10 according to athird embodiment. The measurement system 10 corresponds to themeasurement system 10 described with reference to FIG. 2B except for thefollowing differences. A description of similar elements will beomitted, and same or functionally the same parts are provided with thesame reference number.

In contrast to the measurement system 10 of FIG. 2B, the measurementsystem 10 shown in FIG. 2C also has the external trigger input 14connected to an input of the switch matrix 40. Thus, the switch matrix40 has the same number of inputs for receiving the trigger event signalsas the number of outputs of the comparator 42 and a further input forreceiving the binary trigger signal generated by the external triggerinput 14.

The switch matrix 40 has a number k of outputs connected to the triggerlogic unit 38 for supplying the binary trigger signals and the triggerevent signals selected as trigger sources to the trigger logic unit 38for further processing based on the set of trigger conditions. Thenumber k may be the same number as the numbers n and/or m or it may be adifferent number.

Thus, the binary trigger signal and/or the trigger event signal receivedby the switch matrix 40 may be selected as at least one trigger sourcesimilarly to what has been described before.

FIG. 3 is a flow diagram illustrating a method 500 for generating atrigger signal for a measurement system according to an embodiment ofthe present disclosure.

In a first step 510, at least one external analog input signal isreceived and converted to into at least one corresponding digital inputsignal. Furthermore, the method comprises the step 520 of receiving anexternal trigger signal and comparing the external trigger signalagainst a trigger threshold signal for generating a binary triggersignal which may or may not be performed in parallel to step 510.

In a next step 530, a trigger event signal based on the at least onedigital input signal is generated. Finally, in step 540 the triggerevent signal and the binary trigger signal are combined yielding acombined trigger signal.

The method 500 may be implemented by the measurement system according toany one the embodiments of the present disclosure.

According to some embodiments, the a digital signal processing unit 16comprises a field-programmable gate array (FPGA), anapplication-specific integrated circuit (ASIC), a digital signalprocessor (DSP), a microprocessor, etc. Hence, at least some componentsof the digital signal processing unit 16 are established by the FPGA,ASIC, microprocessor, and/or DSP. In some embodiments, the whole adigital signal processing unit 16 is established by a FPGA, ASIC and/orDSP.

In some embodiments, each block of any of the block diagrams orflowcharts described herein and/or illustrated in the FIGURES, or anycombination thereof, may be implemented in part by computer programinstructions, e.g., as logical steps or operations executing on aprocessor in a computing system. These computer program instructions maybe loaded onto a computer, such as a special purpose computer or otherprogrammable data processing apparatus to produce aspecifically-configured machine, such that the instructions whichexecute on the computer or other programmable data processing apparatusimplement the functions specified in the block diagrams and associateddescriptions, etc., and/or carry out the methods described herein. Theterm computer can include any computing device or processing structure,including but not limited to a processor (e.g., a microprocessor), acentral processing unit (CPU), a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field-programmablegate array (FPGA), a system on a chip (SoC), or the like, or anycombinations thereof. Of course, any of these computing devices orprocessing structure can include or be associated with discrete digitalor analog circuit elements or electronics, or combinations thereof.

In some embodiments, one or more units of the a digital signalprocessing unit 16, include one or more computing devices, such as oneor more of the computing devices listed above, associated with a memorystoring logic modules and/or instructions for carrying out thefunction(s) of the digital signal processing unit 16 and/or any of itssub-units, either separately or in any combination. In an embodiment,one or more units of the a digital signal processing unit 16 includescombinations of circuits and computer program products having softwareor firmware instructions stored on one or more computer readablememories that work together to cause the power device to perform one ormore methodologies or technologies described herein. In otherembodiments, the digital signal processing unit 16 or one or more unitsof the a digital signal processing unit 16 includes hardware circuitimplementations (e.g., implementations in analog circuitry,implementations in digital circuitry, and the like, and combinationsthereof).

The present application may also reference quantities and numbers.Unless specifically stated, such quantities and numbers are not to beconsidered restrictive, but exemplary of the possible quantities ornumbers associated with the present application. Also in this regard,the present application may use the term “plurality” to reference aquantity or number. In this regard, the term “plurality” is meant to beany number that is more than one, for example, two, three, four, five,etc. The terms “about,” “approximately,” “near,” etc., mean plus orminus 5% of the stated value. For the purposes of the presentdisclosure, the phrase “at least one of A, B, and C,” for example, means(A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C),including all further possible permutations when greater than threeelements are listed.

The principles, representative embodiments, and modes of operation ofthe present disclosure have been described in the foregoing description.However, aspects of the present disclosure which are intended to beprotected are not to be construed as limited to the particularembodiments disclosed. Further, the embodiments described herein are tobe regarded as illustrative rather than restrictive. It will beappreciated that variations and changes may be made by others, andequivalents employed, without departing from the spirit of the presentdisclosure. For example the features of the described embodiments may becombined with one another in any combination. Accordingly, it isexpressly intended that all such variations, changes, and equivalentsfall within the spirit and scope of the present disclosure, as claimed.

The invention claimed is:
 1. A measurement system having: at least oneanalog channel comprising an analog-to-digital converter configured toconvert an external analog input signal into a corresponding digitalinput signal; an external trigger input for receiving an externaltrigger signal and comprising a first comparator configured to comparesaid external trigger signal against a trigger threshold signal forgenerating a binary trigger signal; a digital signal processing circuitconfigured to: receive said digital input signal; generate at least onetrigger event signal based on said digital input signal; receive saidbinary trigger signal; and generate a combined trigger signal dependenton a set of trigger conditions based on said at least one digital inputsignal, said at least one trigger event signal and said binary triggersignal; and an acquisition memory, wherein said at least oneanalog-to-digital converter is connected to said acquisition memory forstoring said at least one digital input signal or samples of said atleast one digital input signal in said acquisition memory, wherein saidacquisition memory is connected to said digital processing circuit forreceiving said combined trigger signal, and wherein said digital signalprocessing circuit is configured to control the acquisition memory basedon said combined trigger signal to select a portion of said at least onedigital input signal stored in the acquisition memory or a portion ofsamples of said at least one digital input signal stored in theacquisition memory.
 2. The measurement system according to claim 1,wherein said binary trigger signal is continuous in time and hasdiscrete values.
 3. The measurement system according to claim 1, whereinsaid digital processing circuit comprises a second comparator, whereinsaid second comparator is configured to receive at least one thresholdvalue and is further configured to compare said digital input signalagainst said at least one threshold value for generating said at leastone trigger event signal.
 4. The measurement system according to claim3, wherein at least one of said trigger threshold signal or said atleast one threshold value is a single voltage value for an edge-triggeror a pulse width for a pulse width trigger or a glitch trigger.
 5. Themeasurement system according to claim 1, wherein said digital processingcircuit comprises a switch matrix, wherein said switch matrix isconfigured to pre-process at least one of said digital input signal orsaid at least one trigger event signal.
 6. The measurement systemaccording to claim 5, wherein said switch matrix is further configuredto pre-process said binary trigger signal.
 7. The measurement systemaccording to claim 5, further comprising at least two of the at leastone analog channel, each one of the at least two analog channels beingconfigured to receive a respective external analog input signal and toconvert the respective external analog input signal into a correspondingdigital input signal, thereby obtaining at least two digital inputsignals, wherein said switch matrix is configured to select signals tobe processed by said digital processing circuit from said at least twodigital input signals.
 8. The measurement system according to claim 1,wherein said digital signal processing circuit is configured to controlthe acquisition memory based on said combined trigger signal to:selectively store said at least one digital input signal or samples ofsaid at least one digital input signals in said acquisition memory. 9.The measurement system according to claim 8, further comprising adisplay, wherein said digital signal processing circuit is configured toprovide from the acquisition memory to said display for displaying saidat least one digital input signal, samples of said at least one digitalinput signal, a selected portion of said at least one digital inputsignal, or a selected portion of samples of said at least one digitalinput signal.
 10. The measurement system according to claim 1, whereinsaid set of trigger conditions is configured to provide a qualifiedtrigger.
 11. The measurement system according to claim 1, wherein saiddigital processing circuit is configured to selectively combine, basedon said set of trigger conditions, at least said digital input signaland said binary trigger signal as trigger sources for generating saidcombined trigger signal.
 12. The measurement system according to claim1, further comprising at least one external digital input for receivingan external digital input signal, wherein said digital processingcircuit is further configured to generate said at least one triggerevent signal based on said digital input signal from saidanalog-to-digital converter and further on said external digital inputsignal.
 13. The measurement system according to claim 1, wherein saiddigital signal processing circuit comprises at least one of a FPGA or anASIC.
 14. The measurement system according to claim 1, furthercomprising a user interface for receiving a user input, wherein at leastone of said trigger conditions, said trigger threshold signal, athreshold value associated with a comparator of said digital processingcircuit, or a trigger source are based on said user input.
 15. Themeasurement system according to claim 14, wherein the trigger source isselected out of each of said at least one analog input channel, saiddigital input channel and said external trigger input.
 16. A method forgenerating a trigger signal for a measurement system, said methodcomprising the steps of: receiving at least one external analog inputsignal and converting said external analog input signal into at leastone corresponding digital input signal by an analog-to-digitalconverter; receiving an external trigger signal by an external triggerinput and comparing, by a first comparator, said external trigger signalagainst a trigger threshold signal for generating a binary triggersignal; generating, by a digital signal processing circuit, a triggerevent signal based on said at least one digital input signal; combining,by said digital processing circuit, said trigger event signal and saidbinary trigger signal, thereby forming a combined trigger signal,storing, in an acquisition memory, said at least one digital inputsignal or samples of said at least one digital input signal, whereinsaid acquisition memory is connected to said digital processing circuitfor receiving said combined trigger signal, and wherein said acquisitionmemory is controlled by said digital signal processing circuit based onsaid combined trigger signal to select a portion of said at least onedigital input signal stored in the acquisition memory or a portion ofsamples of said at least one digital input signal stored in theacquisition memory.